Accelerators for dry pipe valves in automatic sprinkler systems



Feb. 4, 1958 HERKIM ER ,9 ACCELERATORS FOR DRY PIPE VALVES IYN :AUTOMATIC SPRINKLER SYSTEMS Filed April 16. 1956 Filj- El.

Y 'Arm/P/m s 2,822,052 Fatented Feb. 4,1958

fifice ACCELERATORS FOR DRY PIPE VALVES IN AUTOMATIC SPRINKLER SYSTEMS Harold Herkimer, New York, N. Y., assignor to The Raisler Corporation, New York, N. Y., a corporation of New York Application April 16, 1956, SerialNo. 578,353

7 Claims. (Cl. 16919) This invention relates to accelerators for dry pipe valves in automatic sprinkler systems.

It is an object of the present invention to provide an accelerator which is extremely reliable in operation, is easy to clean and has a highly predictable reaction time, being far superior in this last respect to present day accelerators.

Conventionally an accelerator is triggered by a pressure differential'sensing element which is exposed to two air pressures, one being the actual air pressure in the dry pipe line and the other a reference pressure that customarily is the standing pressure in the line immediately before breaching. The'two pressures usually are obtained by interconnecting a pair of chambers througha gas flow restricting element so that when the line is tight the pressures are equal, being maintained in balance under varying temperature conditions by slow passage of gas through said element but becoming unbalanced when pressure in the line suddenly drops.

For many years it has been the practice to use for said element a solid body having a tiny opening, e. g. a minute hole in a disc. But due to the very small diam eter of the opening, it has been particularly susceptible to clogging and is very diflicult to clean. It is, moreover, owing to its minute dimensions, extremely easy to damage. For instance, if the element merely is cleanedby scraping a blade over its surface, the porelike opening may be partially closed by flow of metal around the mouth of the opening. In addition to these difliculties the diameters of openings in different discs, even though bored by the same hair-like drillbit, are not the same because of wear and the very fine size of the bit. Hence the reaction time of the pressure differential sensing element, and therefore of the accelerator, has been unpredictable and in actual practice has fluctuated beyond the accepted safe variation.

It is a specific object of the instant invention to provide in an accelerator of the character described a. gas flow restricting element which avoids, all, of the foregoing drawbacks, which is difiicult to clog but easy to clean, which is ruggedand hard to deform and which has, above all, a highly regular'and predictable gas flow coefficient.

Other objects of the invention in .part willbeobvious and in part will be pointed out hereinafter.

The invention accordingly consists in thefeatures of construction, combination ofelements, andarrangements of parts which will be exemplified in the construction hereinafterdescribed; and of which the scope of'application will be indicated 'in the appended claims.

In the accompanying drawings, in which is shown one ofithe various possible embodimentsof the invention:

Fig.1 1 is-afragmentary schematic view of a dry pipe sprinkler system having a dry pipe valve provided with an accelerator including the present invention;

Fig. 2,.isan enlarged1 vertical central sectional .view of the, accelerator? shown in ,Fig 1; and

Fig. 3 is an enlarged fragmentary view of a-portion of the gas flow restricting element.

Referring now. in detail to the-drawings, the reference numeral 10 denotes a. sectionof a dry pipe automatic sprinkler system including a high pressure water line 12, a dry pipe valve 14, an accelerator 16; a sprinkler pipe 18 and sprinkler heads 20.

The dry pipe valve 14 comprises a housing 22 having extending upwardly from its bottom a water passageway 24 to which the cold water pipe 12 is connected. The rim 26 of saidpassageway is preferably horizontal and acts as a seat for an oversize clapper 28 pivoted to the housing as by a hinge 30 at one, side thereof. The clapper comprises, for example, a rigid metal disc with an elastomeric facing. Another seat 32 for the overhanging periphery of the clapper is provided. around the rim 26 and lies in the same horizontal, plane as said rim. The annular space 34 between seat 32 and the passageway 24 is vented; to the atmosphereand also is connected at the outside o'f'the housing to apipe 36. A sprinkler pipe 38 is connected to the housing at the top thereof on the upp erside'ofthe flap opposite from the water passageway 24; Thugchambers a and b are provided above and below the clapper, respectively.

As is well kn'owrl'thedry pipe air pressure on the upper face of the, clapper over-balances the sum of the water pressure in the passageway 24 and the atmospheric pressure in the'annular space 34, and this keeps the clapper such as pipe 18, to which it is connected as by anelbow joint 42', saidpipe 18 being shown to include sprinkler heads 20 depending therefrom; The sprinkler system above the valve 14 is filled'with compressed air. The sprinkler heads are plugged by a low melting metal alloy.

The accelerator 16 comprises a pressure chamber 44 and body 46. Said chamber is substantially in the shape of an inverted cup and includes atubular side wall 48 and a flat top 59. The top is provided with a central tapped aperture 522, and a flat-portion 5d surrounds said aperture; Near the bottom ofthe side wall aninwardly projecting annular fiange 56 is formed; said flangebeing provided with an annular step 58 in the inner lower face thereof. An internally threaded skirt-6t) depends below the flange.

The body 46 likewise is cup-shaped and includes a tubular side wall 62 and a bottom 64. The side wall-has an annular flange 66 extending radially outwardly from the topthereof; said flange andwall are so dimensioned that the flange is snugly receivable in the depending skirt 60 of the pressure chamber. The body includes a tapped opening 68 in the bottom, said opening being adapted to receive a male threaded drainage plug 69. A tapped opening 7% in the side wall receives a clean-out plug. '71. An inlet opening 72 is providedin the side wall and receives ,anend-of a pipe 74 whichisconnected. at its other end tothe sprinkler pipe 38. All of the pipe connections described herein may be conventional, e. g., the inlet opening is tapped and the end of the pipe received therein is threaded.

A tapped outlet opening 76 is formed'in the bottom 64, said opening receiving in the manner described above a: pipe 78.joinedby an'elbow jointfit) to pipe 36'which extends from the annular space .34 in the dry pipe'valve.

The-chamber and body are secured toone another by an externally threaded clamping ring 82 adapted to screw into depending skirt 60 of the pressure chamber and having a portion 83 abutting the under surface of the flange 66 of the body. A fluid-tight connection between the pressure chamber and body is effected by placing an elastomericdiaphragm 84. between the lower surface of pres sure: chamber flange 56 and the top surfaceof body flange 66.

A discharge disc 86 fabricated from an elastomeric asaaoaa material is provided in the body and caps the outlet opening 76. The disc is carried by a discharge clapper 88. The clapper is mounted for oscillatory movement by a lever 90 to one end of which it is secured as by a bolt 94 extending through the lever and screwed to the disc. The other end of the lever is located beneath a push rod bracket 96 and has a tapped aperture in which an adjustment screw 100 is threaded. An adjusting lock nut 102 is located on said screw.

The lever is mounted to rock about a fulcrum F near its center. To this end, a hinge pin 104 is rotatably disposed in an opening near the center of the lever and is held in place by a cotter pin 108. The hinge pin is carried on a lower bracket 109 secured to the body as by fitting a plug 110 at the bottom of the lower bracket into a well 112 formed in the bottom of the body. The disc 86 and clapper 88 are sufficiently heavy to keep the opening 76 closed under normal circumstances.

The bracket 96 is secured by a pin 116 to a push rod 118 located centrally in the body. The push rod is vertically shiftable in a stationary bottom guide 120 and a stationary central guide 122. A collar 124 is attached to the upper end of the push rod as by a pin 126. A diaphragm plate 128 is provided in the body, said plate having an externally threaded upwardly projecting integral central tube 130 that provides an internal well 132. Formed integral with said tube is an elongated upwardly extending hollow stem 134 the bore of which runs into the well 132. Said stem projects into the pressure chamber. The collar 124 abuts the top of the well 132 and rests on a spring 136 seated on a peripherial flange 138 on the central guide 122 so as to carry the weight of the push rod, collar 124, and bracket 96 and thereby prevent overbalancing of the clapper 88.

The diaphragm 84 extends inwardly over plate 128 to the outside of the tube 130, and a plate washer 140 is disposed on top of the diaphragm. Said washer is flared upwardly and outwardly and is of such size that its outer edge 142 is located in the step 58 of the flange 56. A diaphragm nut 144 is disposed above the washer and clamps the plate, diaphragm and washer together to form a fluid-tight joint. Upward movement of the plate is limited by abutment of the edge 142 of the washer against the roof 146 of step 58.

Spring 136 maintains the push rod and collar in abutment against the step of the plate wall. This causes the entire plate assembly to be biased upwardly so that the outer edge of the plate washer 140 abuts the roof of the step. Thus the plate assembly and push rod assembly move together vertically between an upper position defined by abutment of the step and washer and a lower position defined by abutment of the lower end of the push rod' against the bottom of the body, a recess 148 being provided in said bottom to receive said end.

The upper end of the stem 134 is externally threaded and is threadably received in the tapped lower end of a sleeve 150 having an externally threaded upper end. Said sleeve extends through the aperture 52 in the top of the pressure chamber. A tapped tube 152 is screwed onto the upper end of the sleeve and includes a screen 154 secured therein in any conventional manner. A pressure chamber cap 156 which is externally threaded near the bottom thereof is screwed into said aperture 52. Said cap includes an annular flange 158 substantially parallel to and disposed in vertical registry with the flat portion 54 of the pressure chamber top. An elastomeric gasket 160 is compressed between said flange and said flat portion whereby the seal of the cap and pressure chamber is rendered fluid-tight.

Pursuant to the invention, an air restriction disc 162 is provided in the sleeve 150 near the top thereof. Said disc is disposed on a seat 166 in the sleeve and is held in place by a flanged-over section 168 formed above the seat. The connections between the sleeve and stem, and

4 disc and sleeve are fluid-tight, being rendered so by close tolerances and tight attachment of these parts to one another.

The restriction disc comprises material having the property of slowly passing gases, and according to the invention the restriction disc is made of porous, i. e. permeable, metal. As will be explained in greater detail hereinafter, the accelerator is set with air pressure equal in the pressure chamber and body. The only path for passage of air between the body and pressure chamber is through the opening in the well 132, the bore of the stem 134 and the restriction disc 162. The abutment of collar 124 against the top of the well 132 is not fluidtight and indeed said collar may be centrally perforated to freely pass air. Thus, on sufficient drop of air pressure in the body, the pressure in the pressure chamber forces the plate downwardly thereby actuating the accelerator to open the clapper 88 because the restriction disc is adapted to not pass air rapidly enough to permit equalization of pressure prior to movement of the diaphragm plate.

One purpose of the disc passing air at all is to permit equalization of pressure in the body and pressure chamber for the purpose of setting the accelerator. It is readily apparent that unless the pressure chamber has at least as high a pressure as the body, the accelerator will not work. Another purpose is to avoid premature actuation of the accelerator and thus the dry pipe valve by slight variations of pressure in the sprinkler system such as are encountered when the temperature in a building drops in the evening and which would cause the dry pipe pressure to fall below the reference pressure were it not for the balancing action of the disc. On the other hand, the disc must not allow passage of air between the body and pressure chamber rapid enough to prevent actuation of the accelerator when the pressure in the body drops. Thus, proper operation of the restriction disc is essential for reliable performance of the accelerator.

The screen 154 serves to keep larger particles of dirt from clogging the restriction d'isc. Porous metal is inherently not very subject to clogging and can be cleaned readily by washing in an organic solvent. It is important that the disc not become clogged because if it does the accelerator cannot be set and will not operate when needed.

With porous metal discs the desired slow leakage of air is obtained inexpensively and reliably. Moreover, they can be made uniform so that a particular size and type of disc will have a predetermined rate of air leakage. This is of advantage because it permits the reaction time of the accelerator (i. e. time in which the accelerator will be actuated upon opening of a sprinkler head), to be gauged for a given set of temperature and pressure conditions. Also, it permits accelerators to be adapted to have different reaction times for different conditions by varying the porosity of the discs. The reason why the reaction time can be gauged is as follows: the drop of pressure in the body corresponds to that in the sprinkler pipes when a sprinkler head opens. The drop in pressure in the sprinkler pipes very often is quite slow, as for example when the open sprinkler head is at the end of a long dry line. To some extent, the drop in pressure in the body is equalized by leakage of air from the pressure chamber through the restriction disc into the body. This leakage, however, does not prevent a ditference in pressure between the chambers from arising which is sufficient to actuate the accelerator in time to spray the fire before it has reached disastrous proportions. And the time it takes to reach this dilference depends in part on the rate of leakage through the restriction disc. Accordingly, by selecting a desired rate of leakage for the known physical constants of the system the reaction time for the most remote head can be set properly.

mange-s2 Porous discs forpusei in,-.the'-present invention can be made in any wellalrnown .manner, preferably; by. sintering:te'chniques. For.- example, aapordus' disc can be made from iron as-follows: irTon powder: is mixed with: comminuted' lead oxide: in the ratio of :70 partsi of iron to 30 parts of lead oxide'in azball-mi'll-runtil' the lead oxide completely coats the iro'npowder. The' coated powder is placedin moldshaving the: desired configuration and is sintered at temperatures. ranging from 1;00'0=' to 2,000 P. and for periods rangingv from minutes to an hour according to the temperature utilized. This is done under reducing conditions, as,- for, example, in an atmosphere of hydrogen, nitrogen, etc. The result of the sintering is reduction ofthe lead oxide to lead in situ. Cooling. is accomplished ,under, non oxidizing conditions, and the final product is a solid mixture of lead and iron. The porosity of the final article can be controlled by the amount of mixing, the sintering temperature, the particular sizes of the powders and other variable conditions. Thus, discs can be produced having the same predetermined porosity and therefore the same rate of leakage of air for given temperature and pressure conditions by simply making the conditions under which the discs are produced and the sizes of the discs the same. Of course, the rate of leakage can be changed by changing the thickness and diameter of the discs. Still further, it is not necessary that the porous metal employed be in circular shape. Any other shape can be used, and it is simply necessary that it be properly fluid-tightly seated in the sleeve.

The accelerator operates as follows: As already explained, the spring 136 maintains the diaphragm plate, the bracket 96 and push rod in their uppermost position, i. e., in the normal position of these elements. With said elements in said normal position, the screw 100 under the bracket 96 is adjusted to barely touch said bracket so that the discharge clapper maintains the outlet opening of the body closed. The lock nut is used to retain this setting of the adjustment screw.

To set the accelerator, a valve 168 located in pipe 74 is closed to disconnect the inlet opening 72 from the sprinkler system pipe 38. The drain plug 69 is removed to allow any water in the accelerator to drain out, the screw 100 is turned to just touch the bracket 96 and then the plug is replaced. Next, the pressure in the sprinkler pipe system is raised to the requisite amount necessary for maintaining the dry pipe valve closed until such time as a drop of pressure caused by opening a sprinkler head makes it necessary for the dry pipe valve to open. Water under pressure now is admitted to the line 12. The valve 168 now is opened, and the pressure in the sprinkler system becomes established in the pressure chamber and body by leakage of air through the restrictive disc.

The accelerator after setting becomes actuated as follows:

When there is a drop of pressure in the sprinkler system, it is immediately reflected in a corresponding drop of pressure in the body of the accelerator. This causes the diaphragm plate to move downwardly because of the greater pressure in the pressure chamber which cannot be equalized by the slow leakage past the restriction disc. Downward movement of the diaphragm plate as already explained causes the discharge clapper to be raised with the result that the compressed air in the sprinkler system vents through the accelerator body and through pipe 36 to the annular space 34 and thence to the atmosphere. The path of air is from the sprinkler pipe 38 through pipe 74 into the body of the accelerator through the inlet opening 72, out of the body through the outlet opening 76, and through pipes 78 and 36 to the annular space 34 below the clapper 28. The raised air pressure below the clapper 28 and the accelerated outflow of air above it quickens opening of the clapper and thus admission of water to the dry pipe whereby actuation of the accelerator not only relieves the pressure in 6 the sprinklensy'stem which-would otherwise impede opening of the dry pipe valv'e but-also has the effect ofpositively aidingin-the" openingof the valve.

Itthus will-lbe seen that there is: provided adevice in whichtheseveral objects of this invention are' achieved, andwhich iswell adapted to meet the conditions of practical use.

As various; possible embodiments. might be made of the above invention, and asvari'ous changes might be made in the embodiments above set: forth, it is to be understood that all matter herein set forth or shown in the accompanying drawings is: to be interpreted as illustrative and notina limiting sense.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1. In an accelerator of the class described for use in a dry pipe sprinkler system, the combination of a pressure differential sensing member having two chambers, means connecting one chamber to the dry pipe whereby the pressure in said chamber is the same as that of the dry pipe, said one chamber having an outlet opening, a valve for said outlet opening, means connecting said member to said valve for opening said valve when the pressure in said one chamber is less than the pressure in said other chamber, and a porous metal element located between the two chambers of the pressure differential sensing member and having one surface exposed to the pressure in one chamber and an opposite surface exposed to the pressure in the other chamber.

2. In an accelerator of the class described for use in a dry pipe sprinkler system, the combination of a pressure differential sensing member having two chambers, means connecting one chamber to the dry pipe whereby the pressure in said chamber is the same as that of the dry pipe, and a porous metal element located between the two chambers of the pressure differential sensing member and having one surface exposed to the pressure in one chamber and an opposite surface exposed to the pressure in the other chamber.

3. A combination as set forth in claim 2 wherein the porous metal element is composed of sintered metal powders.

4. A combination as set forth in claim 2 wherein the porous metal element includes sintered iron powders.

5. In an accelerator of the class described for use with a dry pipe sprinkler system, the combination of a pressure chamber having an opening, a hollow body having an opening, means securing said body and said pressure chamber fluid-tightly to each other with the openings in registry, an inlet opening in said body adapted to be connected to the dry pipe sprinkler system, an outlet opening in the body, a discharge valve closing said outlet opening, means mounting said discharge valve for movement between a closed position in which it fluid-tightly covers the outlet opening and an open position in which it is spaced from said opening, a member mounted in the body for movement between two positions responsive to a difference in pressure between the chamber and body, means connecting the aforesaid mounting means for the valve to said member for movement with said member, the mounting means, connecting means and member being so located with respect to each other that in the position occupied by the member when the pressure is equal in the pressure chamber and body the valve is closed and in the position occupied by the member when the pressure in the body is less than that in the pressure chamber the valve is open, means fluid-tightly separating the opening of the pressure chamber from the opening of the body, said member having a portion extending through said last-named means, said portion having a through opening, and a porous metal restriction device located at said por tion and adapted to pass air very slowly.

6. In an accelerator for use in a dry pipe sprinkler system which accelerator comprises a pressure diiferential sensing member having two chambers, means conmeeting one chamber to the dry pipe whereby the pressure in said chamber is the same as that of the dry pipe, said one chamber having an outlet opening, a valve for said outlet opening, and means connecting said member to said valve for opening said valve when the pressure in said one chamber is less than the pressure in said other chamber: a porous metal element located between the two chambers of the pressure differential sensing member and having one surface exposed to the pressure in one chamber and an opposite surface exposed to the pressure in the other chamber.

7. In an accelerator for use in a dry pipe sprinkler system which accelerator comprises a pressure differential sensing member having two chambers, means connecting one chamber to the dry pipe whereby the pressure References Cited in the file of this patent UNITED STATES PATENTS 1,790,467 Grifiith Jan. 27, 1931 

